NMR study of localization and mobility of 1‐phenylethanol enantiomers in homochiral metal‐organic sorbent Zn₂(bdc)(S‐lac)(dmf)

Abstract

Structural features of localization of chiral isomers of 1-phenylethanol (R-PhEtOH and S-PhEtOH) and their mobility activation in homochiral metal-organic [Zn2 (bdc)(S-lac)(dmf)] sorbent were studied with (1)H and (13)C NMR methods. (13)C NMR chemical shifts do not show obvious advantage of selective interaction of molecule guests. But activation molecular mobility of S-PhEtOH and R-PhEtOH clearly indicates that stabilization of [Zn2(bdc)(S-lac)(dmf)]·S-PhEtOH structure is more preferable than stabilization of [Zn2 (bdc)(S-lac)(dmf)]·R-PhEtOH structure.

Thermal effects in guest–host systems: [Zn2(bdc)(S‐lac)(dmf)]•PhEtOH: A DSC and NMR study

“…Above 187 K, a narrow line with the characteristic half‐width below 1 kHz appeared in the center of the spectrum and increased in intensity with temperature. This line, as shown earlier, corresponds to the PhEtOH molecules located on the surface of [Zn 2 (bdc)( S‐ lac)(dmf)] crystals …”

“…Thus, NMR data obtained in this work and in our earlier study do not reveal sharp changes in the mobility of guest molecules in the region of phase transitions. This fact testifies that phase transitions are not related to any disorder of the guest molecules in the host pores.…”

“…According to the earlier obtained 1 H NMR data on the mobility in [Zn 2 (bdc)( S ‐lac)(dmf)]·( R‐ or S ‐)PhEtOH complexes, the dynamic disorder of guest molecules are not observed up to decomposition temperatures of the samples . Figure displays the temperature dependence of the half‐width of 1 H NMR spectral lines in [Zn 2 (bdc)( S ‐lac)(dmf)]· RS ‐PhEtOH.…”

“…The MAS 13 C NMR spectra of the [Zn 2 (bdc)( S ‐lac)(dmf)]·( R ‐, S ‐)PhEtOH and [Zn 2 (bdc)( S ‐lac) (dmf)]· RS ‐PhEtOH are shown in Figure . The assignment to the NMR spectral lines for [Zn 2 (bdc)( S ‐lac)(dmf)]·( R ‐ and S ‐)PhEtOH has been done previously . It is easy to see that the fundamental differences in 13 C NMR spectra of the [Zn 2 (bdc)( S ‐lac)(dmf)]·( R ‐ and S ‐) PhEtOH and [Zn 2 (bdc)( S ‐lac)(dmf)]· RS ‐PhEtOH are not observed.…”

“…This line, as shown earlier, corresponds to the PhEtOH molecules located on the surface of [Zn 2 (bdc)(S-lac)(dmf)] crystals. 11 The MAS 13 C NMR spectra of the [Zn 2 (bdc)(S-lac) (dmf)]·(R-, S-)PhEtOH and [Zn 2 (bdc)(S-lac) (dmf)]·RS-PhEtOH are shown in Figure 4. The assignment to the NMR spectral lines for [Zn 2 (bdc)(S-lac)(dmf)]·(R-and S-) PhEtOH has been done previously.…”